Composite materials can be designed with properties, such as toughness, high strength, and low weight, that are useful in many applications where homogeneous materials are less effective or inadequate. For example, fiber reinforced materials, a broad class of composites, typically comprise fibers of a material, such as glass or ceramic, that are embedded in a matrix material, such as plastic or metal, to improve the strength of the matrix material. Fabrication of such reinforced materials can often be difficult, however, because of physical incompatibilities between the fibers and the matrix material.
One method of fabricating multiple ply, continuous fiber reinforced metal matrix composites is the so-called foil/fiber/foil process. In this process, reinforcing fibers are sandwiched between layers of a metal foil. Pressure and heat are then applied to the layered structure for solid state consolidation of the fibers into the metal structure.
The basic foil/fiber/foil process, although adequate for consolidation of large diameter fibers in relatively soft metal matrices, has proven unsatisfactory for consolidation of small diameter, brittle fibers, especially in the form of tow, in relatively hard matrix alloys. For example, at the high temperatures, pressures, and exposure times required for consolidation with creep-resistant alloys or other matrix materials that resist diffusion bonding, the reinforcing fibers receive excessive chemical and mechanical damage during the process without becoming fully consolidated within the matrix. Thus, there is a need for new and effective methods of forming metal matrix composites with fully consolidated fibers.